Multi PGW Support

Introduced in ASN 2.5

Overview

ASN 2.5 introduces Enhanced User Session Identification, allowing additional configurable tunnel and QoS attributes to be included in the user session identification key. This enhancement improves session correlation accuracy in S5/S8 and S11 User Plane (U-Plane) deployments where multiple subscribers may generate traffic with identical inner flow characteristics.

By extending the session key, ASN can distinguish traffic that would otherwise be aggregated into the same user session, improving subscriber correlation and the accuracy of exported session statistics.

Background

In S5/S8 and S11 U-Plane deployments, multiple services and subscribers may share the same transport infrastructure. Different subscribers (IMSIs) can generate traffic with identical:

• IP Address

• Layer 4 Port

• IP Protocol

ASN now supports extending the user session key with configurable outer tunnel and QoS attributes.

User Session Key Enhancement for U-Plane Flow Identification

The following optional attributes can be included in the user session identification key:

Attribute	Description
OUTER_SRC_IP	Outer Source IP Address
OUTER_DST_IP	Outer Destination IP Address
OUTER_DSCP	Outer IP ToS / DSCP
GTP_TEID	GTP-U Tunnel Endpoint Identifier
INNER_DSCP	Inner IP ToS / DSCP

Each attribute can be enabled or disabled independently through configuration.

Session Identification Behavior

Default Behavior

When all new configuration parameters are disabled, the system shall maintain the existing user session identification behavior without any change.

Enhanced Behavior

When one or more additional key fields are enabled, the configured attributes shall become part of the user session identification key.

Session Key Composition

The user session key is constructed using the following fields:

Inner Source IP +
Inner Destination IP +
Inner Source Port +
Inner Destination Port +
IP Protocol +
Outer Source IP +
Outer Destination IP +
GTP TEID +
Outer DSCP +
Inner DSCP

Only the fields enabled through configuration shall participate in session key generation.

For example, if only Outer Source IP and Outer Destination IP are enabled, the session key becomes:

Inner Source IP +
Inner Destination IP +
Inner Source Port +
Inner Destination Port +
IP Protocol +
Outer Source IP +
Outer Destination IP

Kafka and IPFIX Export Behavior

When Enhanced User Session Identification is enabled:

• Kafka topic keys shall be generated using the configured session key composition.

• IPFIX flow keys shall be generated using the configured session key composition.

Memory Utilization

Enabling Enhanced User Session Identification increases memory consumption by approximately 10 MB per processing core.

Non-Impacted Components

The following components are unaffected by this feature:

• Data Center (DC) mode

• Receive Side Scaling (RSS) flow processing

Benefits

• Improves user session identification accuracy in S5/S8 deployments.

• Prevents incorrect aggregation of traffic from different subscribers.

• Reduces IMSI mis-correlation.

• Improves the accuracy of user-level analytics and reporting.

• Supports configurable session key composition without affecting existing deployments.